Regarding some of the points in the first set of questions...

Presuming that the outgasing from the glass wafers is due to adsorbed
water and surface hydroxyls (silanols), RK Iler (The Chemistry of
Silica, 1979) gives the follow information (p 639):
o physically adsorbed water is removed at 115 C, after which point the
rest of the water is present as silanols
o At 150 C, there are about 5 OH groups per square nanometer
o At 800 C, there are about 1 OH groups per square nanometer
o At about 400 C, "somewhat less than half of the hydroxyl groups have
been removed ... These can adsorb water and thus the surface is readily
rehydrated"
o Above 400-450 C, more hydroxyl groups are removed and less of the
surface is readily rehydrated

In practice, we have found that baking glass & quartz at 500+ C for 4-6
h gives a reasonably dry surface over which SU-8 spreads readily.

Chris Blanford

On Thursday, January 31, 2002, at 09:36 AM, Oberhammer Joachim wrote:

> (1) Has anyone information about outgasing of different glass wafers
> (pyrex, quartz)? Do you know about quantitative measurements or
> estimations of it? Do you know, how to avoid it efficiently? (like
> baking the wafers prior to use, ho much does it reduce the
> outgasing?) Is the outgasing much higher compared to "standard"
> Si-wafers? I also would appreciate contacts with manufacturer of
> glass wafers regarding this topic.

--
Christopher F. Blanford
Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR, UK
Phone: (44)/(0)-1865-282603; Fax: (44)/(0)-1865-272690
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